The present disclosure provides a treatment device for lowering electron affinity. The treatment device is capable of performing an electron affinity (EA) surface treatment on a photocathode material or an EA surface retreatment on a photocathode. The present disclosure also provides an electron-beam device provided with the treatment device. An activation chamber is used in a treatment device for lowering electron affinity by vaporizing a surface-treatment material and uses the vaporized surface-treatment material to perform an electron-affinity lowering treatment on a photocathode material or an electron-affinity lowering retreatment on a photocathode. The activation chamber includes one or more holes through which electrons can pass.